Intrauterine growth restriction - and a postulated treatment modality for clinical research and it&#39;s biochemical rationale

ABSTRACT

Intrauterine fetal growth restriction (IUGR) is a very important clinical problem for which no satisfactory treatment is available so far. The current invention of IV hypertonic glucose supplementation to the mother to improve the glucose transfer to the fetus at the intervillous space by improved facilitated diffusion can be a safe and easy way of treating this problem, as the improved fetal blood glucose can lead to fetal lipogenesis that can conserve the fetal O 2  utilization, relieves the associated metabolic derangements of fetal hypoxia, hypercapnea, and acidosis, apart from replenishing the oxidized coenzymes needed for the carbohydrate metabolism. The use of transamniotic fetal feeding (TAFF), studied by animal experiments, can be difficult in humans, because of the dangers of infection, which can be overcome by the use of implantable ports with the sterile patch technique.

[0001] In both developed and developing countries, infant birth weightis probably the single most important factor affecting the neonatalmortality and morbidity. Gruenwald (1963) reported that approximatelyone third of the low birth weight infants were mature and that theirsmall size can be explained by chronic fetal distress, probably due toplacental insufficiency. These and observations by many other led todevelopment of the concept that the birth weight was governed not onlyby the length of gestation but also by the rate of fetal growth.

[0002] Definition—Small-for-gestational age (SGA) infants are thosewhose weights are below the 10^(th) percentile for their gestationalage. Thus approximately 10% of human births are deemed ‘small’ and thesewere shown to be at increased risk for neonatal death.

[0003] Usher and McLean (1969) proposed that fetal growth standardsshould be based on mean values with normal limits defined by plus orminus 2 standard deviations and this definition restricts small forgestational age infants to 3%, compared to 10% when percentiles wereused.

[0004] Etiology—A variety of conditions starting from infections tocongenital anamolies are known to cause intrauterine growth restriction(IUGR). 25-30% will have suffered from uteroplacental insufficiency ofvarious causes and this is the clinical situation we are interested inthis present clinical discussion. Chronic vascular disease especiallywhen it is further complicated by superimposed preeclampsia, commonlycause growth restriction. Conversely preganancy induced hypertension,with out under lying vascular and renal disease, is unlikely to beaccompanied by preeclampsia.

[0005] Fetal nutrition—The maternal diet is the source of the nutritionsupplied to the fetus. There are operational mechanisms in pregnancy tominimize glucose utilization by the mother, there by making it availableto the fetus. One metabolic action of HPL, a hormone, normally presentin the mother, but not in the fetus, is believed to be blocking of theperipheral uptake and utilization of glucose by maternal tissues whilepromoting the mobilization and utilization of free fatty acids. Thefetus is not exposed to the constant supply of glucose, even in normalpregnant women, the plasma levels vary up to 75%. Fats and proteins alsoare transported across the placenta, but they don't play a major role infetal nutrition and growth.

[0006] Having realized what is the major fetal nutrient, it is importantto know how it gets to the fetus and what are the factors that haveeffect on this important intrauterine mechanism. Placenta being theconnecting link between the mother and the fetus, it is relevant toexamine the adverse events that occur in this vital organ in situationslike fetal growth restriction due to placental insufficiency, presumingthat the maternal nutrition is not sub-optimal. Chronic vascular diseasewhen it is further complicated by preeclampsia, commonly causes growthrestriction. So it is relevant to know what happens to the placentalcirculation in disease situations, so that we can search for means toimprove the causative states, though not cure them.

[0007] The Placental Insufficiency in Chronic Vascular andPreeclampsia/Eclampsia Disease States:

[0008] Naeye and Friedman (1979) concluded that 70% of the excess fetaldeaths in preclampsia were due to large placental infarcts, markedlysmall placental size and Abruptio placentae. The microscopical placentallesions were resulted from reduced uteroplacental perfusion.

[0009] Vasospasm—Vasospasm is basic to the pathophysiology ofprecelampsia/eclampsia. It causes resistance to blood flow and accountsfor the development of arterial hypertension. It is likely thatvasospasm itself also exerts a damaging effect on the vessels. More overAngiotensin II appears to have a direct action on the Endothelial cells,causing them to contract. These changes likely lead to interendothelialcell leaks, through which blood constituents including Platelets andFibrinogen are deposited subenthelially (Brunner and Gavras). Thevascular changes together with local hypoxia of the surrounding tissuespresumably lead to hemorrhage, necrosis and other end organ disturbancesthat have been observed at times with severe preeclampsia. With thisscheme, fibrin deposition is then likely to be prominent as seen infatal cases (McKay)

[0010] The principal histopathological feature of placental infarct showfibrinoid degeneration of the trophoblast, calcification, and ischemicinfarction from occlusion of the spiral arteries that normally fill theintervillous spaces.

[0011] Abnormal placentation—Compared to normal women, women destined todevelop preeclampsia may have a poorer physiological response to thedevelopment of the placenta. There appears to be a halt in thetrophoblastic invasion of the spiral Arteries resulting in thediminished blood supply to the placenta and the fetus (Robertson et al1975)

[0012] There may be an antigenic relationship between the placenta andthe kidney (Boss 1965 Curzen 1968) and the pathological lesions found inthe placenta in the cases of pregnancy induced hypertension bear somesimilarity to those found in the kidneys rejected after tranplantation(Robertson et al 1975). The Florescent microscopy studies of renalbiopsies mentioned by Petrucco et al 1974, are in keeping with an immunemechanism affecting the kidneys. Therefore, there is some evidence tosupport a disturbed immunology in women with this condition—a deficientimmune response of the mother to the fetus (Beer 1975).

[0013] The intervillous space: Maternal blood—The intervillous space isthe maternal biological compartment of transfer where the maternal blooddirectly bathes the trophoblast. Substances that pass from the maternalblood to the fetal blood must traverse —1) Trophoblast, 2) Stroma of theintervillous space, 3) Fetal capillary wall. This histological barrierdoes not behave uniformly like a simple physical barrier; thesyncytiotrophoblast either actively or passively permits, facilitatesand adjusts the amount and rate of transfer of a wide range ofsubstances to the fetus. According to Broseus and Dixon (1963), thereare about 120 Spiral arterial entries into the intervillous space of thehuman Placenta at term, discharging blood in spurts that displaces theadjacent villi.

[0014] At least 10 variables are found to be the important factors indetermining the effectiveness of the human placenta as the organ oftransfer—

[0015] 1. The concentration of the substance under consideration, in thematernal plasma and in some instances the extent to which it is bound toanother compound such as a carrier protein.

[0016] 2. The rate of maternal blood flow through the intervillousspace.

[0017] 3. The area available for exchange across the villous trophoblastepithelium.

[0018] 4. If the substance is transferred by diffusion, the physicalproperties of the tissue barrier interposed between the blood in theintervillous space and the fetal capillaries.

[0019] 5. For any substance that is actively transported, the capacityof the biochemical machinery of the placenta for effecting the activetransfer (eg. Specific receptors on the plasma membrane of thetrophoblast).

[0020] 6. The amount of the substance metabolized by the placenta duringthe transfer.

[0021] 7. The area of the exchange across the fetal capillaries in theplacenta.

[0022] 8. The concentration of the substance in the fetal blood,exclusive of any that is bind.

[0023] 9. Specific binding or carrier proteins in the maternal or thefetal circulation.

[0024] 10. The rate of the fetal blood flow through the villouscapillaries.

[0025] Knowing these variables of fetoplacental transfer, it isimportant to focus our attention on those we can alter, control orpositively change to the advantage of improved transfer of the essentialnutrients. The factor 2—improvement of the maternal blood flow throughthe intervillous space can be achieved to some extent by maximum bedrest in left lateral position as soon as the diagnosis of IUGR is made.However the factors 1 and 9 are even more important for the presentdiscussion i.e. trying to improve the concentration of the substanceunder consideration in the maternal plasma and the extent to which it isbound to another compounds such as a carrier protein.

[0026] The factors 2 and 3—i.e. the rate of the maternal blood flowthrough the intervillous spaces and/or the area available for exchangeacross the villous trophoblast epithelium—are the ones that areadversely affected in pathological states affecting the spiral arterieslike in preeclampsia and eclampsia, thus causing decreased placentalperfusion and fetoplacental transfer.

[0027] However knowing we don't have any significant control on factor 2and 3, we should accomplish the goal of improved transfer of essentialnutrients through the controllable property mentioned in factor 1 i.e.increasing the conc. of the substance under consideration, in this case,D-Glucose, the major fetal nutrient which is made available to thefetoplacental unit through selective transfer and facilitated diffusion.

[0028] Brief Description of the Current Invention—Induced MaternalHyperglycemia-

[0029] The most common cause of intra uterine fetal growth restriction(IUGR), is vascular in nature resulting in the placental insufficiency,thus decreasing the transfer of D-Glucose, the most important fetalnutrient, across the placenta. There are other adverse metabolic eventsthat can also happen in placental insufficiency, but the fetus has otheradaptive devices to counter act those derangements, where as there is nomechanism to overcome the chronic fetal hypoglycemia that results infetal growth retardation. The current invention is an easy,biochemically and scientifically sound way of improving fetalhypoglycemia and as a result also other associated metabolic problems ofplacental insufficiency in a surprisingly simple way, about which a veryelaborate supportive biochemical discussion is presented in thefollowing pages to justify the current proposed treatment.

[0030] An accelerated facilitated diffusion can be achieved by creatinga transient hyperglycemia (induced diabetic state) in the mother byintravenous 10-20 hypertonic glucose infusion, up to 50-100 cc. twice orthrice a day, with or with out insulin given subcutaneously, as soon asit is confirmed that IUGR is of vascular in origin. It is interesting tonote that chromosomal anomalies are also associated with reduced numberof small muscular arteries in the tertiary stem villi. Chronic partialplacental separation, extensive infarction, circumvillate placenta,Velamentous insertion of the cord—all these conditions also cause IUGRof vascular origin. One or both the twins affected by IUGR could be dueto decreased trophoblastic area available to each.

[0031] The IV infusion as above, creates a situation like a ‘fetal meal’during which time deprived fetal circulation can receive more glucosepresented in a higher concentration in the same given amount of bloodflow across the intervilous spaces. The carrier protein operating in asub optimal way before becomes maximal in its function during thistransient maternal hyperglycemic phase. After the fetal energy andgrowth requirements are met, Glucose can be stored in the fetal liverand also in the placenta to be used by the fetus during the times ofneed.

[0032] Selective Transfer and Facilitated Diffusion

[0033] Although diffusion is an important method of placental transfer,the trophoblast and chorionic villus unit exhibit enormous selectivityin transfer, maintaining different concentrations of a variety ofmetabolites on the two sides of the villus.

[0034] The concentration of a number of substances which are notsynthesized by the fetus are several times higher in fetal blood than inmaternal blood. The transfer of D-Glucose across the placenta isaccomplished by a carrier mediated, steriospecific, non-concentratingprocess that can be saturated—Facilitated diffusion. Transfer proteinsfor D-Glucose, GLUT-1 and GLUT-3 have been identified in the plasmamembrane (the microvilli) of human syncytiotrophoblast. GLUT-1expression is prominent in human placenta, increases as pregnancyadvances, and is induced by all growth factors. GLUT 3 is also expressedprominentl in placenta, being localized in the Syncyntio trophoblast,and the most distinctive characteristic of GLUT-3 isoform is its lowK_(m) for glucose, meaning that half maximal glucose transfer occurs atlow-concentrations of glucose. More over in response to Insulin action,intracellular GLUT-3 is redistributed to the cell plasma membrane.

[0035] The membrane transport of glucose is illustrated in drawing-1, Itshows that glucose (G) combines with a carrier protein (C) at point 1 toform the compound CG. This combination is soluble in the lipid so thatit can diffuse (or simply move by rotation of the larger carriermolecule) to the other side of the membrane, where glucose breaks awayfrom the carrier protein (point 2), and passes to the inside of the cellwhile the carrier moves back to the outside surface of the membrane topick up still some more glucose to transport it also to the inside. Thusthe effect of the carrier protein is to make glucose soluble in themembrane; without it glucose can not pass through the membrane.

[0036] The rate at which a substance passes through a membrane byfacilitated diffusion depends on the difference in concentration of thesubstance on the two sides of the membrane (this concept being the keypoint of the present treatment postulation), the amount of the carrieravailability and the rapidity with which the chemical (physical)reactions can take place (factors 1, 8, 9). In the case of glucosetransport, the overall rate is greatly increased by insulin. Largequantities of insulin (which can be released by pancreas during a mealor hyperglycemic state) can increase the rate of glucose transport aboutseven to ten fold, though it is not known if it is caused by an effectof insulin to increase the quantity of the carrier protein in themembrane or increase the rate at which the chemical reaction takes placebetween glucose and the carrier (factor 9).

[0037] So it seems only logical to also have the mother get insulin SCor insulin mixed with the infusion of hypertonic glucose. Though thereis intrinsic stimulation of insulin by maternal pancreas, supplementinginsulin can be the sure way of making insulin available at the placentalsite to increase the rate of facilitated diffusion by many fold asdescribed. However the insulin dose does not need to be like for adiabetic patient, because the idea is to induce maternal hyperglycemia,make adequate glucose level available at the placental site, and also toprevent pancreatic exhaustion due to hyper stimulation.

[0038] When IUGR is first suspected as due to placental insufficiency(having excluded the disease states that would not affect the maternalfeto-placental vasculature), the patient has to be hospitalized, withdecreased physical activity with bed rest in the left lateral positionand the fetal surveillance started. At a minimum, this includes fetalmovement charts, clinical and sonographic assessment of fetal growth,amniotic fluid volume, non stress test, contraction stress test,biophysical profile, daily clinical evaluation of the mother andfrequent fetal heart rate monitoring. These parameters can be comparedto the same readings after IV hypertonic glucose treatment is initiated,the protocol of which is not included in this writing.

[0039] The glucose supplementation to the fetus can also be done bytransamniotic fetal feeding (TAFF), the studies of which were only donein animal experiments (pregnant rabbits), but practically difficult inhumans due to the length of the treatment involved, and the danger ofinfection that can be introduced into the amniotic cavity. Thisdifficulty can be overcome by the inventor's novel idea of usingimplantable ports, that are conventionally used for central venousaccess, the most recent version of which is the peripherally insertedcentral catheter (PICC), that can be implanted at the patient's bed sidealso, by a simple abdominal subcutaneous pocket or tunnel.

[0040] This technique can be further perfected by making it totallyaseptic by using a sterile patch at the site of the port, which can bean alcohol swab, before inserting the needle for delivery into, orwithdrawal from the amniotic fluid.

DRAWINGS

[0041]FIG. 1 The membrane transport of glucose

DETAILED DESCRIPTION

[0042] The most common cause of intra uterine fetal growth restrictionis vascular in nature, causing placental insufficiency and thusdecreased transfer of D-Glucose, the most important fetal nutrientacross the placental interface. There are other metabolic derangementsalso caused by placental insufficiency for which the fetus has adaptivedevices to counter act the problems. How ever the placenta is the onlysource of glucose supply to the fetus, and it is severely affected inplacental insufficiency. The current invention of treatment is aboutimproving the amount of glucose presented at the placental interface,and improving the chronic fetal hypoglycemia, and also simultaneouslyimproving the other metabolic derangements in a surprisingly simple wayabout which a very detailed biochemical discussion is made with outwhich the scientific basis of the current invention can not be properlyunderstood. It is relevant here to describe more of the fetomaternalmetabolism of pregnancy with out which the biochemical and clinicalrationale of the current invention can not be adequately explained.

[0043] The Fetomaternal Metabolism of Pregnancy

[0044] The Maternal Metaboism-

[0045] Profound changes occur in maternal carbohydrate and fatmetabolism during pregnancy as evidenced by the increased blood levelsof lactate, pyruvate, and plasma lipid fractions. Fasting blood sugar isnot how ever raised in pregnant woman.

[0046] It has been generally assumed that carbohydrate tolerance isimpaired in pregnancy and thus pregnancy itself constitutes adiabetogenic stress for the woman. The fact that diabetes may firstmanifest during pregnancy (it is possible it could be present earlier,but diagnosed during pregnancy because blood glucose was checked for thefirst time, making the statistical figures of incidence of diabetesduring pregnancy more than it actually is), that the diabetic womenfrequently require increased amount of insulin as pregnancy advances,the occurance of glycosuria during pregnancy—are all cited as evidencein support of this view.

[0047] How ever, the fasting blood sugar is not increased in normalpregnancy, and serial studies of carbohydrate tolerance in healthy womenduring gestation. Tolerance to IV glucose may in fact be improved inearly pregnancy compared with that recorded in non pregnant state.

[0048] Pregnancy is characterized by major physiological adjustmentsaffecting every system of the body. The changes are frequently on ascale other wise unknown in healthy adult life, and have led to widespread misunderstanding and diagnostic confusion. Unless it is realizedthat the pregnant woman is physiologically almost another species whosehealth can be gauzed only against the standards of healthy women in thesame physiological state, disease will be diagnosed where none exists.

[0049] While it is true that the reasons for a decreased ‘glucosetolerance’, or the more relaxed homeostatic control, possibly can not beexplained to the satisfaction of the most skeptical readers, there is noreason for believing it is any thing other than physiological. It can bestated that the maternal changes are purposeful, and directed towardsthe welfare of the Fetus, and in cases where there is explicithyperglycemia, a better explanation is that it is stress of pregnancy.

[0050] Though the carbohydrate tolerance is not reduced in normalpregnancy, the peripheral resistance to insulin is increased. Bloodinsulin levels are in fact raised in pregnancy both in fasting state andafter glucose load. The paradox of increased amount of circulatinginsulin organism or the presence of additional anti insulin factors—likecorticosteroids, catacholamines, and glucagon but the most importantinsulin antagonist is the Human placental lactogen (HPL), a polypeptideproduced by placenta. It cross reacts immunologically with human growthhormone.

[0051] HPL, which is produced in enormous quantities in placenta, causesincrease in free fatty acids (FFA), and in this respect seems moredominant than insulin, because insulin is anti lipolytic. And once thereis increased free fatty acids, the maternal tissue utilize more of it,sparing glucose to be diverted to fetoplacental circulation to beutilized, which is a slow process, because the amount of glucose sparedfrom all the tissues of the maternal body is much more and generalized,compared to what is getting into the fetus, through only the narrowumbilical cord (thus the maternal body acts as the glucose reservoir forthe sustained glucose supply to the fetus). So as long as there is highlevels of glucose, it is going to release insulin from maternalpancreas. However the HPL also prevents insulin's effects on the carriertransporters of glucose, apart from increasing free fatty acids thatcompete with glucose for their own utilization by the maternal tissues.

[0052] The maternal pancreas is only conditioned to produce insulin asglycemic response, but does not perceive that insulin and also glucoseis not being effectively used by the maternal tissues except theplacenta. How ever, this fundamental loop of the body's feed backmechanism which prevails during pregnancy is still not ineffective,because the rise of insulin proportional to the glucose level is neededto enable facilitated diffusion at the utero-placental interface.

[0053] Tolerance to Intravenous Hypertonic Glucose Supplement is InfactImproved During Pregnancy-

[0054] It is of common belief that pregnancy is potentially diabetogenicand tissue resistance to insulin increases, but if the biophysiology ofthe cause and effect of the above changes during pregnancy are analyzed,we can say that it is maternal adaptation, rather than tissueresistance, all these adaptive devices being geared to direct glucose tofetus at the expense of the mother, the maternal tissues having changedtheir way to using FFA more than glucose for energy and growth. Thesematernal adjustments are the result of a over stretched adaptation evenduring normal pregnancy—being so many operational devices put togetherto divert glucose to the fetus, which can not be helped any more duringuteroplacental insufficiency, to increase the amount of glucose to bepresented at the placental intervillous space, though the fetalcirculation is chronically deprived of it's prime nutrients. IV glucosesupplementation is some what similar to but easier than what the bodytissues in pregnancy are trying very hard to do—sparing the mother usingglucose, and diverting it to the fetus. IV glucose should only ease theover stretched adaptive pathways of pregnancy. So there can besufficient theoretical basis to believe that IV glucose supplement isbetter tolerated in pregnancy than in nonpregnant condition. After fewdays of hospitalization, and teaching the protocol to the patient, itcan be done at home also with the help of the home health nurse. Duringthe hospitalization it can also be decided if the insulinsupplementation is necessary or not. Choosing to give the infusion tothe mother in between the meals to make it more tolerable, andphysiologically more suitable, is scientifically very appealing thought.Mid night is also a preferable time though some what inconvenient to themother.

[0055] The transitional hyperglycemia in the maternal blood can alsohelp the fetus to build the glycogen stores in the liver, and fat in thesubcutaneous adipose tissue, after meeting it's energy requirements.This storage helps the fetus to cope with the possible hypoglycemicepisodes. Insulin increases the glycogen deposition in the placenta alsowhich Claude Bernard compared to early fetal liver, or moreappropriately to it's skeletal muscle, because of it's metabolicresponse to Adrenaline and other hormones—is release of lactate, ratherthan glucose. How ever, lactate is still utilized by the fetus,especially by the fetal brain.

[0056] Fetal Blood Glucose Homeostas

[0057] The fetus and the new born are more resistant to anoxia than theadult. Altered rates of glycolysis, in anaerobic conditions is generallygreater than in adult tissues. But the brain that is very sensitive tointerference with it's glucose supply, has little glycogen, and hassimilar rates of glycolysis in aerobic and anaerobic conditions. Studiesshowed that metabolic protection for brain during intra uterine anoxiamay be provided by the ability of the fetal and neonatal cerebral tissueto metabolize substrates other than glucose such as pyruvate, lactate,and acetate. The citric acid cycle can proceed in the absence ofmolecular oxygen, provided that adequate supply of oxidized coenzymesare available. In fetal tissues, the synthesis of fatty acids, a processwhich requires the hydrogen contained in the reduced coenzymes, may beincreased in anoxia. Oxidized coenzymes would thus be reformed andenable the pyruvate produced by glycolysis to be completely metabolizedwith release of further energy i.e. ‘coupling of lipogenesis withglycolysis and citric acid cycle’, by which hypoxia is better tolerated.

[0058] Good amount of glucose availability leads to the followingpathways—

[0059] Glucose availability leads for glucose to be converted intoAcetyl—co A, the Precursor for fatty acid synthesis.

[0060] The Embden Meyerhof pathway of glycolysis, that takes placemostly in the cytosol, produces Dihydroxy acetone phosphate, anintermediary product, which can be converted into glycerol 3-PO₄, byglycerol 3-PO₄ dehydrogenase, with the help of NADH+H which is oxidizedto NAD (Nicotinamide dinucleotide), which in turn, can be utilized inglycolysis—citric acic cycle. Good circulating levels of insulin as innormoglycemic or hyperglycemic conditions, can activate the triglyceride(TGD) formation in the adipose tissue, by activating the acylation ofglycerol 3-PO₄.

[0061] In surplus glucose availability, hexose monophospahte shunt(HMPS), is also activated, producing NADH+H, the hydrogen of which isused in fatty acid synthesis, and HMP shunt also produces ribose sugarsnecessary for DNA, RNA and steroid synthesis.

[0062] NAD is also generated from NADH+H, in the path ways leading tolipogenesis in the extramitochondrial cytosol, wherein, oxaloacetate isconverted into malate, in the process converting NADH+H to NAD, thisstep linked to transfer of reducing equivalents to NADP (thephosphorylated derivative of NAD), involved in fatty acid synthesis.This path way is the means of transferring reducing equivalents fromextra mitochondrial NADH to NADP generating NAD (can be used in glucosemetabolism), and NADH+H that is used in fatty acid synthesis. This pathway also is very important as the link between and in the perpetuationof carbohydrate and lipid metabolism, thus saving oxygen, that iscrucial to the problem of placental insufficiency.

[0063] Activation of fatty acid synthesis by adequate glucoseavailability can generate oxidized coenzyme NAD continuously, by whichglucose helps it's own metabolism to completion, to produce pyruvateinstead of lactate that can proceed into citric acid cycle, and NAD canalso be utilized as the coenzyme in citric acid cycle. The biochemicaldetails of all these mentioned path ways will be discussed in furtherdetails in the following pages.

[0064] The resistance of the fetus and neonate to hypoxia probablydepends on a number of alterations in metabolic patterns in differenttissues, each of which provides a small increase in metabolicefficiency, and hence over all, ensures a greater safety margin duringoxygen lack. As the human fetus grows, the proportion of Linoleic acid(an essential FFA, not synthesized in the body—comes from the maternalblood), in it's subcutaneous fat decreases and the proportion of thePalmitic acid (produced with in the body) increases, and at the time ofbirth, Palmitic acid is twice as much as Linoleic acid. The fatty acidcomposition of the subcutaneous fat of the newborn is similar to that ofanimals given a diet rich in carbohydrate and poor in fat. Raiha (1954),pointed out that synthesis of fat from carbohydrate may provide thehuman fetus with means of decreasing it's oxygen requirements. Ville(1954), has estimated that the triglycerides synthesized during lastmonths of fetal life might save the fetus a maximum of ⅙ th of the totaloxygen requirements. Mylination of the brain is most rapid in the 7 thmonth of the fetal life, during which time the human brain would be mostsusceptible to the effects of under nutrition. Unfortunately, IUGR alsois more pronounced at this period of intra uterine life. Cholesterol andother complex lipids are of special importance in the formation ofmyelin in the developing brain. Fetal tissue can synthesize most (90%),if not all, cholesterol from glucose or acetate. Also in a normal fetus,oxidation of fatty acids (use of fats for energy—i.e. fat catabolism)contributes little towards it's total energy consumption, thus savingsubstantial amounts of oxygen. It is consistent with the finding thatthe FFA levels are low in normal fetus. The respiratory quotient (RQ) offetal tissues in vitro has also been shown to be above unity

[0065] (Roux 1966), indicating that the synthesis of FFA fromcarbohydrate outweighs oxidation of fatty acids.

[0066] Adequate Supply of Glucose Makes Hypoxia More Tolerable—theBiochemical Rationale

[0067] Ability of the fetus to with stand oxygen lack is related to aparticular metabolic change i.e. altered rates of glycolysis andlipogenesis, and indeed the rate of glycolysis in fetal tissues inAnaerobic conditions is generally greater than in adult tissue. Citricacid cycle can proceed in the absence of molecular oxygen provided thatan adequate supply of pyruvate from glycolysis of glucose molecule, andoxidized coenzymes are available.

[0068] 1. With Limited Amounts of Oxygen and also Limited Amounts ofGlucose-

[0069] Glucose metabolism (glycolysis) can proceed upto the productionof pyruvate both in anaerobic and aerobic path ways, producing 2molecules of ATP and 2 molecules of pyruvate (see the path way in FIG.1). After this step, the further pathway changes. In anaerobicconditions lactate is the end product of pyruvate with also theformation of coenzyme NAD.

[0070] With what ever amount of oxygen available, once acetyl Co-A isgenerated, in the extramitochondrial compartment, fatty acid synthesiscan be activated, but further maintenance is only possible byavailability of glucose that can initiate hexose mono phosphate shunt(HMP shunt), that is the chief source of the hydrogen required asNADPH+H, in the reductive synthesis of fatty acids. Other sources ofNADPH include the isocitrate dehydrogenase reaction, and the reactionthat converts malate to pyruvate catalysed by malic enzyme (NADP malatedehydrogenase). All these three pathways are also extramitochondriallike the FFA synthesis itself, and involve abundant supply of glucose,that can generate NADPH necessary for fatty acid synthesis, and theseare also linked to the generation of NAD, the oxidized coenzymenecessary for glucose metabolism, making the ‘coupling of lipogenesisand glycolysis—citric acid cycle’ surprisingly efficient, even with outparticipation of molecular oxygen in these path ways. How ever, withlimited glucose availability in placental insufficiency, the sequence ofevents stop at the level of the production of pyruvate and initiation offatty acid synthesis, both of which can not proceed any further.

[0071] 2. With Limited Supply of Glucose but Adequate Amounts of GlucoseAvailable-

[0072] The metabolic influence of the citric acid cycle extends purelybeyond a catabolic function. By it's perpetual activity, it forms thehub and the central metabolic meeting point for all most all cellularactivity. Nearly all the reactions and substrates of this cyclicalmanoeuvre have a crucial role in the synthesis of multitude of essentialmetabolites e.g. those concerned with amino acids, Purines, Pyramidines,long chain fatty acids and Porphyrin synthesis. Additionally, theoperation of the cycle converts potential chemical energy into metabolicenergy in the form of ATP.

[0073] In the pathway shown in the FIG. 2, it is shown how a surplus ofglucose availability activates both the fatty acid synthesis and TGD(triglyceride) synthesis, and also provide sufficient amount ofoxaloacetate—all these sparing molecular oxygen, and would generateoxidized coenzymes NAD, and NADP that help the maintenance of oxidativepathways like citric acid cycle and glycolysis. Oxygen thus spared, canbe utilized for oxidative phosphorilation, where oxygen need ismandatory, to generate the needed ATP for energy.

[0074] In FIG. 2, glucose in box (1), shows the initiation of citricacid cycle. Glucose in box (2), the additional amount of glucoseavailable, shows the path ways that are activated and perpetuated by theproduction of Pyruvate (3), acetyl CoA (4), and the NADPH+H, throughHMPS, with what ever oxygen that is available from placenta.

[0075] Acetyl CoA, formed by the pyruvate dehydrogenase complex,participates into fatty acid synthesis (5). The hydrogen (6) needed forthe co enzyme NADP (7) to be converted into NADPH+H (8), necessary forthe fatty acid synthesis, is mostly supplied by the hexose monophoshateshunt (9) (HMPS), that takes place in the extramitochondrial cytosol,also the place for fatty acid synthesis. The HMPS is active in adiposetissue in the presence of high circulating glucose. During fatty acidsynthesis NADPH+H (8) is

oxidized to NADP (7). The FIG. 2 also shows NADP (7), the oxidizedcoenzyme, to participates in the reaction that converts isocitrate (10)to a-(alpha) ketoglutarate (11), involving the isocitrate dehydrogenaseenzyme complex. This cycle shows how the most important reaction inlipogenesis i.e. the formation of acetyl CoA (4), and the NADPH+H (8)are initiated by the adequate supply of glucose. The NADP (7) that isgenerated in the fatty acid synthesis, can in turn be further used inthe HMPS, and the oxidized form of NADP is generated here also, thussaving the molecular oxygen.

[0076] The FIG. 2, also shows how the NAD, the oxidized coenzymenecessary for the metabolism of glucose is also generated during theprocess of lipogenesis. Acetyl CoA (4), formed from glucose (2), furtherparticipates in the citric acid cycle (12), along with oxaloacetate (13)(also produced from pyruvate by pyruvate carboxylase, the enzyme thatreplenishes oxaloacetate to the citric acid cycle in the presence ofbiotin). Adequate amounts of oxaloacetate can participate in malateshuttle (14), through the formation of a-ketoglutarate (15). It diffusesinto the cytosol, and the a-ketoglutarate (16), in the cytosol can formoxaloacetate (17), that will react with NADH+H (18), to form malate (19)and NAD (20). The high lighted part of the cycle shows the malateshuttle through the cytosol and the mitochondrion, and in this shuttleNAD is generated from NADH+H, thus also saving molecular oxygen. Thisreaction is linked to the reduction of NADP (7) to NADPH+H, with theconversion of malate (19) to pyruvate (3) by malic enzyme (21). Theformation of a-ketoglutarate (16) is necessary because oxaloacetate(13), can not pass through the mitochondrial membrane.

[0077] Acetyl CoA, the main building block for the fatty acid synthesis,can not diffuse readily into the extramitochondrial compartment, and sothe citrate (22) from the citric acid cycle diffuses into the cytosol,where it undergoes cleavage by ATP citrate lyase (the citrate cleavingenzyme), like the malic enzyme, to form acetyl CoA (23) and oxaloacetate(24). The activity of the citrate cleaving enzyme increases when thereis high glucose availability, which also parallels the activity of fattyacid synthesis. Acetyl CoA (23) is now available for the initiation offatty acid synthesis, and the oxaloacetat (24) can form malate (25) viaNADH+H (26) linked malate dehydrogenase (27) forming NAD (28), followedby the generation of NADPH+H (8), via the malic enzyme (21) with theformation of pyruvate (3). This path way is means of transferingreducing equivalents from extramitochondrial NADH to NADP as shown inthe FIG. 3. Alternatively, malate can be transported into themitochondrian where it is able to reform oxaloacetate. It is to be notedthat the citrate transporter in the mitochondrial membrane requiresmalate to be exchanged with citrate.

[0078] Glycerol-3 phosphate (29), the main ingredient that combines withthe FFA (5) to form TGD (30), in the adipose tissue, is derived from theintermediate product of glycolysis—the dihydroxyacetone phosphate (31),which forms the glycerol-3 phosphate (29), by reduction with NADH+H(32), catalysed by glycerol-3 phosphate dehydrogenase, also forming NAD(33) in the process. The glycerol-3 phosphate, to combine with theFFA—to form the TGD (30) is activated by insulin in glycemic conditions.The

(33) generated in the lipogenesis can be further utilized inglycolysis—citric acid cycle and NADH+H (32), generated in theglycolysis—citric acid cycle, can in turn be used for further synthesisof glycerol-3 phosphate for lipogenesis, thus again replenishing theoxidized coenzymes needed for carbohydrate metabolism as shown in theFIG. 2.

[0079] Both the NAD and NADP thus formed in the process of lipogenesis,can keep up with the maintenance of citric acid cycle, and otheroxidative metabolic pathways. Molecular oxygen thus saved, can be usedto generate ATP in oxidative phosphorilation of the respiratory cycle,where in, the participation of the molecular oxygen is mandatory.

[0080] In the left part of the figure are the NADP and NAD, the oxidizedcoenzymes saved in the different steps of the intimately interrelatedpathways of the carbohydrate and the lipid metabolism.

[0081] The Other Metabolic Derangements in Placental Insufficiency

[0082] It is a legitimate concern, that the treatment of impairedglucose transfer by inducing diabetic state in the mother, can notcorrect the other problems inherent to the placental insufficiency, andall these problems put together would still be detrimental to the fetalwell being. It is also of critical issue that adequate glucoseavailability in hypoxic conditions can lead to anaerobiosis and lacticacidosis, but these concerns need in depth biochemical exploration.

[0083] The notorious metabolic problems of placental insufficiency otherthan hypoglycemia are—1. Hypoxia 2. Hypercapnea 3. Acidosis (includingketoacidosis), and 4. Hyperlactecemia and lactic acidosis, that needs aspecial and separate mention.

[0084] In placental in sufficiency, the fetus has no other way toimprove the hypoglycemia, as there are not any adaptive devicesdeveloped by the fetus, except growth restriction and the placenta isthe only source of glucose supply. So manifestation of hypoglycemia isearlier and more urgently evident, that also leads to the development ofvicious cycle of path ways that worsen the already existent metabolicderangements of hypoxia, hypercapnia, and acidosis.

[0085] How ever, for the above mentioned problems, there are otheradaptive devices efficiently developed by the fetus, or else improved bythe normoglycemic status, so that these metabolic derangements are notas sensitively felt as hypoglycemia. It was already explained in detailhow the normoglycemic status opens the path ways for the lipogenesis,and how this crucial step improves the whole gamut of metabolicderangements caused by placental insufficiency in a cyclicallybeneficial way, by saving molecular oxygen. There are few more benefitsof lipogenesis that will be mentioned in relevant places in thefollowing discussion.

[0086] Hypoxia-

[0087] Impaired oxygen diffusion across the placenta is also theconsequence of placental insufficiency. In the fetus there are manyadaptive devices to protect against hypoxia—

[0088] 1. The high affinity of the fetal hemoglobin for oxygen.

[0089] 2. High fetal cardiac out put (minute volume) in relation tooxygen demand.

[0090] 3. High RBC (red blood corpuscles), count of the fetus, and alsohigh MCHC (mean corpuscular hemoglobin concentration), that can carry20-25 ml. of oxygen/dl, where as the maternal blood can only carry 15.3ml/dl.

[0091] 4. The fetus operates at the steepest part of the oxygendissociation curve, and therefore a relatively large amount of oxygen isreleased from the hemoglobin for a given drop in po₂.

[0092] 5. The fetal systemic metabolic acidosis can be preventedpresumably by the cardiovascular adjustments, unless the oxygen contentfalls below the critical level of 2 mmol/L. There will be compensatoryextramedullary erythroblastemia and macrocytosis.

[0093] 6. Both the fetal and the maternal oxygen association showchanges associated with pH, that give rise to double Bohr effect, whichfacilitates transfer of oxygen from mother to fetus.

[0094] 7. In fetus glucose can be utilized in Embden-Meyerhof path wayof glycolysis which can proceed anaerobically even in the absence ofoxygen, to produce pyruvate, lactate and acetate which can be utilizedby the fetal brain for growth and energy requirements.

[0095] 8. Even low grade lipogenesis spares the use of molecular oxygenin generating the oxidized coenzymes needed for the major oxidativemetabolic path ways, and the triglycerides synthesized during the lastmonths of pregnancy, can save the fetus a maximum of ⅙ th of the totaloxygen requirements, and also the prevention of the use of fat forenergy requirements saves substantial amounts of oxygen, the mention ofwhich was already made.

[0096] Hypercapnea-

[0097] Impaired excretion of carbon dioxide (CO₂), that is exchange ofCO₂ at the placental site, is a reasonable concern in placentalinsufficiency.

[0098] CO₂, like O₂ is a lipophilic molecule that crosses the placentaby simple diffusion, which is regulated by the membrane surface areathickness, diffusion coefficient of the gas in the membrane phase, andthe concentration gradient of the gas across the membrane. CO₂ iscarried in the blood predominantly as bicarbonate, with some bound tohemoglobin, as carboxyhemoglobin. The high hemoglobin content of thefetal blood compared to the mother enables it to carry more CO₂ with agiven pH and pCO₂. As the CO₂ is produced by the fetal metabolism, andraises the fetal blood levels of pCO₂, the gas will diffuse across theplacenta from the fetal to the maternal compartments, provided that thefetal pCO₂ exceeds maternal pCO₂. Maternal pCO₂ falls during pregnancyby about 10 torr as a consequence of hyperventilation. A transplacentalgradient of 10 torr is maintained through the later stages of pregnancy.Maternal hemoglobin has higher affinity for CO₂ than fetal hemoglobin,which gives rise to a double Haldane effect that compliments the doubleBohr effect. The capacity of blood for CO₂ at a given pCO₂ is increasedby the release of O₂, so maternal blood will be able to bind increasingamounts of CO₂, for the same pCO₂ as it passes through the placenta,while the reverse occurs for the fetal blood. This considerably augmentsthe exchange of CO₂ at the placenta.

[0099] The diffusion coefficient of CO₂ is 20 times higher than oxygen,and it's diffusion across the cell membrane is instantaneous. So it'sdiffusion across the placenta can be still satisfactory, even when theoxygen diffusion is moderately impaired.

[0100] It is interesting to note that CO₂ is required in the initialsteps of fatty acid synthesis that involves the carboxylation of acetylCoA to melonyl CoA (made possible by good glucose availability). In thesynthesis of Palmitate, 7 molecules of CO₂ are used, and the same numberliberated subsequently. How ever, this cyclic engagement of CO₂ in thefatty acid synthesis, relieves the placenta of some of the burden ofit's disposal.

[0101] Urea synthesis by the fetus increases as pregnancy advances, andsignificant amounts of CO₂ combines with ammonium in the process of ureasynthesis, and it is excreted as the fetal urine into the amnioticfluid. This is also a very important way of significant amounts of CO₂disposal by the fetus.

[0102] Acidosis-

[0103] Fatty acid synthesis not only generates oxidized coenzymes, butalso uses hydrogen ions. 14 hydrogen ions are used in the synthesis ofPalmitate from actyl CoA, and melonyl CoA.

[0104] So during later month of pregnancy, the amount of lipogenesisthat takes place, can dispose off enormous amounts of H ionconcentration from the fetal blood. During hypoglycemia, there will notbe any lipogenesis. On the other hand, lipolysis and beta oxidation isinitiated for energy requirements (also made more prominent by decreasedinsulin levels due to hypoglycemia). But in the absence of glucose andlack of oxaloacetate, fatty acid oxidation produces ketone bodies whichare moderately stronger acids. Once they are formed, even if glucose ismade available, the ketone bodies are oxidized in preference to glucoseand fatty acids, thus saturating the oxidative machinery. So even whenthere is enough oxygen, in the absence of glucose, ketone bodies areformed and the fetus is still going to be acidotic. Beta oxidation ofpalmitate itself produces 14 hydrogen atoms apart from furtherproduction of ketoacidosis. So normoglycemia can compensate for hypoxia,but oxygen can not compensate for hypoglycemia and the related metabolicconsequences.

[0105] Hyperlactecemia and Lactic Acidosis-

[0106] Insulin increases glucose uptake and glycogen deposition by theplacenta and 80% of placenta glycogen is anaerobically metabolized tolactate. It can be freely diffusable across the placenta either into thematernal or fetal circulation, or into the amniotic fluid. Bycotransport with hydrogen ions (there is active HMPS in the placenta),lactate is probably transported as lactic acid from the placenta intothe fetal circulation. The fetal tissues, especially the fetal brain canutilize lactate, but when it accumulates in excess amounts, it can causefetal acidosis.

[0107] Giving the mother IV glucose, during fasting and mid night, avoidthe maternal production of ketones (which is not uncommon even in normalpregnancy). Prevention of maternal acidosis can help for more of lacticacid to be disposed of by maternal circulation instead of the fetalcirculation, at the placental site.

[0108] Production of lactic acidosis can be prevented by initiation oflipogenesis and triglyceride formation during glucose availability,during which time the Glycerol-3 phosphate (the building block of TGD)synthesis from dihydroxyacetone phosphate of glycolysis, can beinitiated, that involves conversion of NADH+H to NAD, which can befurther used in glycolysis, to produce pyruvate rather than lactate.Also during glycemic conditions, under the influence of insulin, whenlipogenesis is activated, lactate also like pyruvate and acetyl CoA, isconverted into fat.

[0109] Amniotic fluid lactic acid level can be a tool to control theamount of glucose to be given to the mother, because the raised glycogencontent in the placenta will cause enhanced placental lactateproduction.

[0110] The above discussion emphasizes the need for glucose more thanany thing else to counter act—not only the hypoglycemia but also theconsequences of the metabolic derangements as a result, that would alsoperpetuates the other direct adverse effects of the placentalinsufficiency.

[0111] Adequate amounts of glucose availability precludes the need ofutilization of fats for energy requirements in fetuses withuteroplacental insufficiency, and conserves oxygen. Utilization of fatfor energy requirements as in beta oxidation, not only in starvation butalso in conditions of normal feeding—probably accounts for about halfthe total oxygen consumed by the whole body. With out adequate glucose,fetal body stores of fat are utilized, making the hypoxia worse.Economides and associates (1990), who measured plasma TGD, demonstratedhypertriglyceridemia that correlated with the degree of fetal hypoxemia.

[0112] Barker and colleagues at the united kingdom medical research unithave over 20 years researched the causes of adult mortality andmorbidity, related to fetal and adult life (Fraser and Cresswell 1997),and found increased risk of hypertension, and atherosclerosis in thecontest of IUGR. It could be attributable to the mode ofhypertrigyceridemia produced in the IUGR fetuses that could bepersistent for significant part of intrauterine life.

[0113] Experimental results in animal and human atherosclerosis studiessuggests, that the fatty streak represents intimal lesions resultingfrom the focal accumulation of lipoprotein in the vascular intima.Recruitments of leukocytes to the nascent fatty streak and theiradhesion to the vascular adhesion molecule 1 (VCAM 1), and intercellularadhesion molecule 1 (ICAM 1) of the vascular intima is further madeeasier due to sluggish laminar flow because of polycythemia andhyperviscosity of the blood in IUGR. In this set up at least some amountof thrombotic reaction in the focal atheromatous area is possible. Asper the ‘Virchow's triad’, the thrombosis of the vessel wall depends on3 factors—the velocity of the blood flow, the viscosity of the blood,and the nature (injury) of the vessel wall, all of which are present inthe IUGR fetuses in an adverse way. So in these babies the ground workis already laid in the intra uterine life, that can easily progress andmanifest into atherosclerosis and hypertension in adult life. Even thesmallest lesion of intra uterine life can be magnified as the babygrows, and in adult life they can assume significant proportion, justlike a mole or a scar we see on a child's face that would becomeproportionately bigger as an adult.

[0114] Insulin is a potent positive stimulus for lipogenesis andnegative stimulus for lipolysis. It inhibits the activity of the hormonesensitive lipace, reducing the release of not only FFA from the fatstores, but also glycerol. In IUGR there is prolonged and persistenthypoglycemia causing hypoinsulinemia resulting in unopposed action oflipoprotein lipase by other hormones like TSH, GH, Glucagon and ACTH,that cause lipolysis. However, because of the lack of oxygen needed forbeta oxidation of these FFA, the FFA in the blood are not used. Aslipogenesis is prevented by lack of insulin, the esterification of theFFA in the blood results, causing hypertriglyceridemia. In a new borngrowth restricted infant with poor development of striated muscle, andabsence of adipose tissue, the baby's plasma and the vestigial pancreascontained no insulin (Hill 1978).

[0115] Neonatal Hypoglycemia

[0116] The level of the circulating glucose just before and soon afterbirth could be as low as 50 mg %, even in apparently normal babies andit could be worse in placental insufficiency.

[0117] There is inadequate or absent glycogen stores in the liver andalso impaired fetal ability to release glucose from what ever glycogenstores that are available. Also the limited supply of glucose iscompromised during delivery, and further cut off after delivery,compounded by explosion of physical activity in different areas of thebody, including vigorous crying of the baby that was in ‘suspendedanimation’ in utero. That is why, in anticipation of this problem mostobstetricians recommend IV glucose during delivery and early feeding ofthe baby after birth.

[0118] Vitamins and Other Essential Nutrients-

[0119] It can be stated that the passage of all the essential nutrientsthrough the placenta are impaired in placental insufficiency. Thiamineand other B-complex factors would not be an exception. Thiamine isessential for carbohydrate metabolism in it's catalytic role ofconversion of pyruvate to acetyl CoA, by the pyruvate dehydrogenasecomplex. If the fetus is deficient in it, substantially increased supplyof glucose can be over whelming to the fetus and can cause accumulationof pyruvate and also can cause lactic acidosis, and all the path wayswhere glucose and pyruvate are utilized, would come to a halt. So,planned oral supplementation of 100 mg. of thiamine would increase thelevels of thiamine presented at the intervillous space, thus ensuringrequired amounts getting into fetal circulation. Only small amounts arestored in the body (25-30 mg), and it's daily need increases as thecarbohydrate intake increases. This hypothesis of thiamine deficiency ofthe fetus may not be practically found in all the fetuses with IUGR, butas there is no way to know it easily, additional supplements at leastwould not harm. Niacin or nicotinic acid (or Tryptophane, an essentialamino acid from which it can be synthesized), from which NAD and NADPare produced in the body, and Riboflavin, from which FAD (flavin adeninedinucleotide) is produced in the body, are also essential for thecarbohydrate metabolism. So also, the folic acid and phosphatesupplements are useful. For patients with IUGR it is a good idea toadvice the diet mostly of carbohydrates, both simple and complex, forimmediate and sustained release of hexose sugars, and proteins and fatsonly as per the pregnancy requirements, but rich in essential aminoacids and essential fatty acids, and the vitamins and minerals—calledIUGR diet. The idea is based on the advantage of mostly carbohydrateutilization by the fetus, and fat anabolism in the fetal body, and nofat catabolism through intrinsic or extrinsic supplies. Snacks of thesame formula can also help improving the low blood glucose levels inbetween meals and midnight.

[0120] A Case Study

[0121] It is of practical interest to mention about a successful fetalout come of a severely growth restricted fetus treated with hypertonicglucose. This single case study was done by me, in 1984, on aprimigravid woman in her early twenties, who was found to have severelygrowth restricted fetus in the middle of second trimester. She was wellnourished, and from good socioeconomic back ground, and there was noobvious etiological factors, or associated medical problems that couldaccount for the IUGR. After observing the growth of the fetus by fundalheight for 3-4 more weeks, it was confirmed that the fundal height didnot increase, and the patient had severely compromised fetus. As thepregnancy was quite remote from term, and as the reduced physicalactivity, and bed rest in the left lateral position did not help, 20% IVhypertonic glucose, 50 cc. twice daily, was started, and in two to threeweeks, there was immediate catch up of fetal growth, and at term shedelivered a healthy baby of normal weight. No adverse effects due to theinduced transient maternal hyperglycemia, was expected or observedduring the pregnancy, and the patient tolerated the treatments verywell.

[0122] The observed growth restriction was severe, but just with glucosesupplementation, the mother delivered a normal healthy fetus at term,and none of the associated problems that can be expected due toplacental insufficiency like hypoxia, and hypercapnia were found, whichcould have been evident by at least by some amount of fetal distress andlowered apgar score, which also supports the fact that in this set up,with mere normoglycemia the fetus can take care of the multitude ofpossible metabolic problems by itself.

[0123] The Amniotic Fluid Nutritional Supplement-

[0124] Nutritional supplement into the amniotic fluid (AF) isscientifically attractive proposition, as it avoids the ratheruncomfortable situation of interfering with the maternal carbohydratemetabolism. The phenomenon of intrauterine fetal swallowing can be takenadvantage of in this modality of treatment. 5% of glucose can be safelyinstilled into the amniotic fluid, with out adversely effecting theosmotic forces. A brief description of the origin, chemistry andproperties of the AF as the aquatic environment of the fetus, isrelevant to the present discussion.

[0125] The composition, turn over, and volume of AF depends on exchangesof molecular water and electrolytes between fetal and maternal plasmaand AF, occurring across the fetal skin and the membranes and also onbulk flows—inflows due to fetal micturition, and out flows due to fetalswallowing. There are columnar cells with secretary features in theamniotic epithelium during early pregnancy, but later the amnion becomesavascular, when the turn over of the AF is maximal. So any contributionof AF by amnion, except in early pregnancy is unimportant.

[0126] Until increasing stratification and keratinization significantlyreduces the permeability of fetal skin, AF is derived mainly as afiltrate of fetal plasma, by diffusion across the skin. During earlypregnancy it's composition therefore resembles closely that of fetalextra celluar fluid—marginally lower sodium, and slightly higher urea inthe AF than in fetal plasma, are due to the intermittent passages ofvery small amounts of hypotonic urine by the fetus from the end of firsttrimester.

[0127] When fetal skin becomes impermeable, the AF is ‘exteriorized’from the continuum of water and electrolytes in the fetal extracellularbody fluids. As a result a close relationship is no longer maintainedbetween the concentrations of the electrolytes and other diffusiblesubstances (and therefore osmolality) in fatal extracellular fluid andthe AF. From about 20 weeks to term, AF osmolality and sodiumconcentration are reduced steadily and the concentration of the urea andcreatinine increases. There is how ever continued simple diffusion inboth directions across the fetal membranes, presumably mainly the amnioncovering the placenta, so that the AF is far from being a relativelystatic pool, apart from the intermittent bulk flows of fetal micturitionand swallowing. Towards term, AF water is probably replaced about everythree hours, by the constant exchange with the mother as much as 500 ml.of water per hour. This water exchange occurs via the fetus, fetalsurface of placenta, and through the surface of the umbilical cord.

[0128] 5% glucose which is isotonic with the extra cellular fluid of thematernal serum should be isotonic with the amniotic fluid, because thenormal osmolality of the maternal and the fetal plasma is in the rangeof 260-275 mosm/kg. and so also is the osmolality of AF from 20-30 weeksof pregnancy. Instillation of 100 cc of 5% glucose twice daily, is asupplementation of 10 G. of glucose that would amount to 41 calories tothe fetus, and if necessary, it can be administered thrice daily also.Even if AF is replaced every 3 hrs., still substantial amounts get intothe fetal body.

[0129] Studies of transamniotic fetal feeding (TAFF) of pregnant rabbitmodels were conducted by Mulvihill et al in 1985, using 10% dextrosesolution which has been associated with increase in fetal weight. However the studies of Flake et al with solutions of dextrose, amino acids,and lipids alone, or in combination did not reverse the growthrestriction, seen in the natural runt rabbit fetus. The reasons forthese controversial results can be only postulated. Too much ofdextrose, with not enough of required vitamins needed for carbohydratemetabolism (presuming the rabbit's biochemistry as similar to human),could be over whelming to the fetal well being as already discussed. Toomuch of lipid supplements, with and with out dextrose, can be a stressto the oxidative machinery of the fetus, as beta oxidation is an oxygenconsuming pathway, which would make the existing hypoxia worse, and theco administration of dextrose not very beneficial.

[0130] The Technique of Transamniotic Fetal Feeding (TAFF)-

[0131] The TAFF in human subjects is not as easy as it is in animalexperiments, because the duration of TAFF is much longer, and theintroduction of infection into the amniotic fluid can be a real danger,which can be directly proportional to the duration of the TAFF, and thenumber of the punctures involved. It will not be easy for the mothereither. So to make it possible, with out the fear of infection, and alsoto make it practically feasible to the mother, the recent innovation ofimplantable ports (originally discovered for central venous access) canbe used, that needs only one time insertion, and can be functional untilthe spontaneous or elective delivery of the fetus is done, and the newerversion, the peripherally inserted central catheter (PICC), can beinserted at the patient's bed side also.

[0132] Implantable ports are central venous access devices that consistsof a subcutaneously implantable reservoir, containing self sealingseptum that can with stand over 2000 needle punctures. In the case ofPICC, the reservoir is made up of a small titanium port, that is placedin a subcutaneous pocket or tunnel over the abdomen in an easilypalpable and easily cleanable location, and is accessed using a Huberneedle for withdrawal or delivery. The port has the advantage ofrequiring little daily care, and therefore interferes less with thepatient's daily activities. The catheter used in this device is apolyurethane catheter placed via an abdominal skin cut down, andthreaded into the amniotic cavity, and can be safely done with ultrasound guidance, to avoid the placenta. However the whole length of thecatheter as used for the central venous access is not needed for uterineaccess, and only the required length can be cut, depending upon thepatient size, to be used for threading. After the access is confirmed,and having at least 5 cms. size of the catheter in the amniotic sac, thecatheter is then connected to the titanium port that is placed in thesubcutaneous pocket. This design also is an easy maintenance both by thepatient, and the health care worker, with only a single 5 ml. salineflush, being recommended once a week, when the catheter is not in use,and even less frequent flushing if heparinized saline solutions areused. The implantable ports have a reported catheter related sepsis rateof 3%, thrombosis of 1%, and a prospective rates of 0.06 pocketinfections, and 0 bacteremic episodes per 100 catheter days.

[0133] The Sterile Patch Technique-

[0134] To make the use of the implantable ports 100% infection free,other novel techniques can be used to make the needle entry siteabsolutely sterile. For this, during every day use, instead of using theneedle on the naked skin of the port site, after cleaning the areathoroughly, a 2″ square sterile alcohol patch, holding only it's edgeswhile taking out of it's pouch, can be used on the port site. The needlecan be inserted through the alcohol swab, thus totally avoiding contactwith the naked skin. After the required amount of the nutrients aregiven, the needle can be taken out, with the alcohol patch still inplace. This makes both the entry and the exit of the needle done totallyunder aseptic precautions with no skin contact at all, even if the skinis not thoroughly cleaned, especially if done at the patient's home. However, the patient and the home health nurse have to be thoroughly taughtabout the danger of infection if not done as instructed, and wearingsterile gloves, still has to be practiced during the use of the portwith the alcohol patch.

[0135] The Nutritional Supplements-

[0136] The amount of dextrose that should be given to the patient shouldbe individualized. It could be detrimental to the fetus, if too much ofglucose is given in situations of severe placental insufficiency, whenhypoxia can be severe, that could lead to anaerobiasis and lacticacidosis, that the fetus can not handle. Or 5 L of oxygen by nasalcanula, can be administered to the mother during and for 2-4 hours afterthe glucose supplementation, but not continuously. Research studies onO₂ administration were done that yielded controversial results. Theoxygen, during the increased supply of glucose, would help aerobicglycolysis of the administered carbohydrate. It is a good idea to startwith small amounts of glucose supplements and progressively increase.Until the glucose required by any mother with IUGR fetus can bedetermined, monitoring the AF lactic acid levels is a good idea, as itcould be a reflection of too much glucose that the fetus can not handle.The danger of excessive glucose supplements to a hypoxic fetus is morein TAFF, because at least in IV glucose supplementation the amount thatgets to the fetus is controlled by the placenta, that would be directlyproportional to the severity of hypoxia secondary to the placentalinsufficiency.

[0137] The Rationale for Nutritive Treatment Instead of Early Delivery

[0138] 1. IV or TAFF glucose (dextrose) treatment to the mother iseasier, physically and emotionally less traumatic, and less invasive,compared to the treatment modalities involved in caring for thepremature IUGR baby in the NICU.

[0139] 2. The incidence of cesarean section can be more for the electivepreterm delivery, with it's associated complications to the mother,especially when there are associated medical problems also.

[0140] 3. Uncertainaties of the fetal out come and the anxiety that isunavoidable for both the parents and the obstetrician can be over comeby delivering a grown and also a mature baby.

[0141] 4. Cognition—though the literature mentions that severedisabilities are low with deliveries as early as 24-26 weeks, even milddisabilities like ADHA (attention deficit and hyperactivity) is asignificant problem, especially if it can be avoidable. There is no wayto know what the child's IQ ‘would have been’ if the intra uterine staywas prolonged and the IUGR treated. For the cognitive evaluation of thebaby during subsequent years after birth, the right comparable parameterof the child's genetic IQ is never known, to be compared to thephenotypical IQ, to know what the child is actually missing. So the mostimportant parameters of comparison is lacking, and one can only say thatthe child is not mentally retarded, but can not say how much IQ dropcould have resulted. The comparison with the general population is notstatistically accurate, because the comparison here involves theindividual child's genetic (inherent) and phenotypical (acquired) IQ.Even siblings of the same parents can be so different, to make astatistically significant comparison.

[0142] 5. The treatment to the mother is cost effective.

[0143] 6. Termination of the pregnancy early and the subsequentmanagement of the baby can be done only in well equipped centers withNICU and the hospitalization can be long, but the treatment of themother can be done in small settings. In motivated intelligent patientsthe treatment can be done at home also with the help of the home healthnurse.

[0144] 7. Complications attributable to preterm deliveries were found tobe indistinguishable from the term infants only between 32-34 weeks. Theincidence of the respiratory distress syndrome was found to be as highas 6% even at 35-38 weeks delivery.

[0145] 8. Neonatal hypoglycemia, polycythemia, and hyperviscosity of theblood (secondary to chronic hypoxia) can be avoided with glucosenutritional supplements and prolonging intrauterine stay. Earlydiagnosis of IUGR and treating with glucose will also prevent fetaltriglyceridemia, and as mentioned in the recent studies, the developmentof hypertension and atherosclerosis in adult life.

[0146] 9. It should be the aim of the obstetrician to not only deliver anormal child, but also a child with the full potential it is geneticallyendowed with.

[0147] The elaborate biochemical discussion was necessary because it hasmany clinical Implications that need to be understood by the practicingclinician, without which confident and intelligent management of theIUGR fetus and it's mother can not be optimal.

1. The new treatment modalities for the intra uterine growth restriction(IUGR) of the fetus, which is mostly due to vascular insufficiency ofplacental origin, for which no safe and satisfactory treatment exists inthe medical field so far, and the current claims are for the newinventions of treatment and the techniques used for safely implementingthis inventions, and also the in depth biochemical rationale discussed,as an applied scientific basis supporting the treatment.
 2. The claimsare for the new invention of administering intravenous hypertonicglucose (dextrose), to the mother twice or thrice daily, with or without insulin in between meals and midnight, that would induce transienthyperglycemic state in the mother, thus increasing the concentration ofthe glucose presented at the placental site to increase the rate offacilitated diffusion within the same given amount of blood flow acrossthe placental intervillous space, which usually is impaired in IUGR ofvascular origin, and the facilitated diffusion of the prime fetalnutrient, the D-glucose, at the placental site itself being dependent onthe conc. of glucose, the substance under consideration, on the twosides of the membrane, and in some instances, the extent to which it isbound to another compound such as carrier protein.
 3. The claims are forthe applied principle, where in, the facilitated diffusion of glucoseacross the placenta, is over all greatly increased to 7-10 fold, by theincreased levels of circulating insulin due to the induced hyperglycemiaof the mother, by the administered hypertonic glucose intravenously, andalso the insulin that can be given subcutaneously in selected groups ofpatients, to prevent pancreatic exhaustion, or to ensure it's presencein the maternal blood, the insulin being the hormone that has positiveeffect on the transfer protein for D-glucose, by causing theredistribution of intracellular GLUT-3, across the cell membrane at theplacental site.
 4. The claims are for the applied principle ofinitiating and maintaining lipogenesis in the fetus, by increasing theavailability of glucose in maternal circulation by intravenous glucose,the lipogenesis in turn saving the molecular oxygen, regenerate theoxidized forms of coenzymes NAD and NADP, that are needed forcarbohydrate metabolism like glycolysis—citric acid cycl, and the hexosemono phosphate shunt (HMPS)—i.e. the ‘coupling of lipogenesis andglycolysis-citric acid cycle’, and the molecular oxygen saved can beutilized in oxidative phosphorylation to produce ATP, for which therequirement of molecular oxygen is mandatory.
 5. The claims are for theFIG. 2, created by the author—inventor, that coordinates the pathwaysthat show the coupling of the lipogenesis and the glycolysis—citric acidcycle, and the cycle also shows how the enhanced carbohydrate metabolisminitiates and maintains lipogenesis, and how lipogenesis inturnreplenishes NAD and NADP necessary for carbohydrate metabolism.
 6. Theclaims are for the applied principle of induced maternal hyperglycemiainhibiting the fat catabolism (utilization of lipids for energyrequirements) in the fetus that would save the fetus at least ⅙ th ofoxygen expenditure (as beta oxidation by which the fats are catabolized,is a high oxygen consuming path way), thus improving fetal hypoxia, andthe insulin secreted in glycemic states also positively contributes tothe situation, as insulin is antilypolytic.
 7. The claims are for thenew postulation of how the initiation and maintenance of lipogenesis inthe fetus (due to the increased glucose availability by induced maternalhyperglycemia) can improve hypercapnea of the fetus, because in thesynthesis of fats, for example, in the synthesis of Palmitate fromacetyl CoA and melonyl CoA, 7 molecules of CO₂ are cyclically engaged inthe process, thus relieving the placenta of some of the burden of it'sdisposal, apart from the excretion of CO₂ into the fetal urine, in theform of urea also.
 8. The claims are for the postulation how the inducedmaternal hyperglycemia, and as a result improved fetal blood glucoselevels can improve fetal acidosis, because the induced lipogenesis notonly generates oxidized coenzymes, but also uses hydrogen ions, and inthe synthesis of Palmitate from acetyl CoA and melonyl CoA, 14 H ionsare used, and the amount of lipogenesis that takes place in the fetus inthe later months of pregnancy can help dispose off enormous amounts of Hion concentration from the fetal blood.
 9. The claims are for thepostulation, how the induced maternal hyperglycemia and improved fetalblood glucose can prevent fetal acidosis, by preventing beta oxidation(in the absence of glucose) that can lead to ketoacidosis, which canhappen even when there is enough of oxygen, the postulation that canemphasize the fact that the normoglycemia of the fetus can compensatefor hypoxia due to placental insufficiency, but O₂ can not compensatefor the hypoglycemia and it's related metabolic consequences.
 10. Theclaims are for the postulation, that giving IV glucose to the mother inbetween meals and mid night can prevent ketosis in the mother (which canhappen even in normal pregnancy), and preventing the ketosis in themother can help more of the lactic acid being disposed off from thematernal circulation instead of the fetal circulation.
 11. The claimsare for the postulation that the induced maternal hyperglycemia and thusimproving fetal blood glucose levels can prevent lactic acidosis byinitiation of the formation of glycerol 3 phosphate during which processNAD is produced that can be used in glycolysis to produce pyruvaterather than lactate, and also during the improved glycemic status of thefetus, lactate like pyruvate, is converted into fat.
 12. The claims arefor the postulation how the induced maternal hyperglycemia and theimproved fetal blood glucose levels can also improve fetalhypertriglyceridemia, by inhibition of lipoprotein lipace by insulinproduction in the normoglycemic status of the fetus.
 13. The postulationof utilization of the IUGR diet—rich in carbohydrates, with only fatsand proteins as per the pregnancy requirements (but with definitecontributions of essential amino acids and fatty acids and also goodamounts of vitamins especially the B-complex factors), the idea based onthe advantage of mostly carbohydrate utilization by the fetus, and fatanabolism in the fetal body and no fat catabolism through intrinsic orextrinsic supplies.
 14. The claims are for the technique of using theimplantable ports, originally discovered for the central venous access,where in, the access is one time insertion only, preferably with theultrasound guidance to prevent injury to the placenta, and the port hasa titanium reservoir kept in the subcutaneous pocket or tunnel of thematernal abdomen, that can with stand 2000 needle punctures, and thepolyurethane catheter used along with the port can be cut to be adjustedin it's size, as per the requirement of the maternal size, the mostrecent model of these ports being the peripherally inserted centralcatheter (PICC), that can be inserted even at the patient's bed side,and these ports are easy maintenance, and interferes less with thepatient's daily activities.
 15. The claims are for the sterile patchtechnique, that would decrease the chances of introducing infection intothe amniotic cavity to zero, where in, a 2″ square alcohol swab heldonly at it's corners, being kept on the port site, and the needleinserted through it into the amniotic sac, and the patch stays even whenthe needle is with drawn, by which the contact of the needle with thepotentially unclean naked abdominal skin can be totally avoided bothduring entry and exit of the needle, this technique being especiallyuseful if the mother is being taken care of at home, by the home healthnurse for the TAFF.
 16. The claims are for monitoring the amniotic fluidglycogen levels, where in, the excess lactic acid levels of the AF canreflect too much of glucose, disproportional to hypoxia, beingadministered, which can cause lactic acidosis, the danger of which canbe more in TAFF and administering O₂, 2-5 L by nasal cannula during andfor 2-4 hrs, after the nutritional supplements, but not continuously,can encourage aerobic glycolysis in the fetus.